Railway signaling track-circuit regulator



March 11, 1930. s. M. LUCAS 1,750,233

RAILWAY SIGNALING TRACK CIRCUIT REGULATOR Filed Nov. 22, 1927 INVENTAOR1 5 M A u 0a s,

Patented Mar. 11, 1930 UNITED STATES PATENT: OFFICE SAMUEL M. LUCAS, orPITTSBURGH, PENNSYLVANIA, ASSIGNOR To THE UNION SWITCH & SIGNAL COMPANY,or SWISSVALE, PENNSYLVANIA, A CORPORATION or PENNSYLVANIA RAILWAYSIGNALING TRACK-CIRCUIT REGULATOR Application filed November 22, 1927.Serial No. 234,935.

My invention relates to railway signaling track circuit regulators, andhas for an ob- .ject the provision of novel and improved means forpreventing excessive energization of the track relay when the trackballast is dry, and, consequently, has relatively high resistance.

I will describe several forms of track circuit regulators embodying myinvention, and will then point out the novel features thereof in claims.a

In the accompanying drawing, Fig. 1 is a diagrammatic View showing atrack circuit having applied thereto one form of regulator embodying myinvention. igs. 2 and 3 are views showing modifications of the regulatorshown in Fig. 1 and also embodying my invention.

Similar reference characters refer to similar parts in each of theseveral views.

Referringfirst to Fig. 1, the reference char- 4 insulated joints 2 toform a track section. I

This section is provided with a track circuit comprising the rails ofthe section, a source f I -in which equation E is the applied potential,e is the over-voltage, and 1" is the internal resistance of the cell.Considering this equation, it is obvious that when E is a variable ofcurrent connected across-the rails at one point, and a track relay Rhaving a winding connected across the railsat another point. As hereshown, the source of track circuit current is atransformer T having itssecondary connected across the rails 1 and 1 and having its primaryconnected with a source of alternating current which is not shown in thedrawing. A limiting impedance 3 is interposed between the secondary oftransformer T and one of the track rails in accordance with usualpractice.

In a track circuit of the type just described, it is necessary to soadjust the source of current that it will maintain the normal operatingvoltage across the relay winding during the lowest value of ballastresistance, that is, during the time of maximum saturation of theballast with water. When the ballast resistance rises, however, thevoltage provided to prevent an increase of current in the relay due toincrease of voltage across the track rails at the point at which therelay is connected with the rails.

In accordance with my invention, I provide a regulator connected acrossthe rails adjacent the relay and so adjusted as to conduct current whenand only when the voltage across the relay winding rises a given amountabove the normal operating value. As shown in Fig. 1, this regulator isan electrolytic cell of such nature that a gas is evolved when currentflows through the cell, and current will not flow through the cell untilthe potential between the electrodes exceeds a definite value known'asover-voltage. Vhen the applied potential exceeds the over-voltage, thecurrent which flows through the cell is limited only by the internalresistance of the cell, that is,

, m E e between zero and maximum, no current will flowthrough the celluntil E exceeds 6, but

when E does exceed e, if r is small, the current through the cell willincrease very rapidly with increase of'E. The combination of electrodesand electrolyte is so chosen that e, the over-voltage of the cell, isslightly higher than the normal operating voltage of I the relay R. Itfollows that when the ballast resistance is low, no current will flow--through the cell C, and the relay R will then receive all of the energytransmitted to the relay end of the track section. When the bal- ,.lastresistance rises, however, current will .flow through the cell G as soonas the potential across the relay exceeds the over-voltage of the'cell.By suitably proportioning the .cell to they track circuitcharacteristics, the consequent in urlous eflects unless means are cellcan be made to preventany decided increase in thecurrent through the.relay, andso to prevent injurious eflects on the relay due toover-energization.

It may not always be possible to secure the most economical operation ofthe relay when the relay is designed for an operating voltage whichwould match with the overvoltage of a given electrolytic cell. In suchcases a transformer may be interposed between the cell and the trackrails, as shown in Fig. 2. Referring to this view, the transformer A hasits primary connected across the track rails and its secondary connectedwith the electrodes l and 5 of the cell C. The transformer A has suchratio that the over-voltage of the cell 0 is substantially equal to thenormal operating voltage of the relay R multiplied by the ratio of thetransformer. v

Referring now to Fig. 3, the regiilatingdevice in the form here shown,comprises two electrolytic cells C and C each having a tantalumelectrode and a lead electrode immersed in a solution of sulphuric acid6. A cell of this character has a much higher resistance in onedirection than in the other direction, and, consequently, it isnecessary to oppositely connect two cells in multiple when the source ofcurrent for the track circuit is alternating.

Although I have herein shown and described only a few forms of trackcircuit embodying my invention, it is understood that various changesand modifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention. Y

Having thus described my invention, what I claim is:

1. In a railway signaling track circuit of the type comprising trackrails, a source of current connected across said rails, and a trackrelay having a winding connected across said rails,the combination withthe aforementioned instrumentalities 'of an electrolytic cell connectedacross said rails and adjusted to conduct current when and only when thevoltage across said relay winding is above a given value. 1

2. In a rallway signaling track clrcuit'of the type comprising trackrails, a track relay having a winding connected across said rails, and asource of current also connected across said rails and adjusted tomaintain the normal operating voltage across said relay winding duringthe lowest value of ballast resistance, the combination with theaforementioned instrum'entalities of an electrolytic cell connectedacross said rails and adjusted to conduct current when and only when thevoltage across said relay winding rises a given amount above the normaloperating value. p

3. In a railway signaling track circuit of the type comprising trackrails, a track relay having a winding connected across said rails,

and a source of current also connected across said rails and adjusted tomaintain the normal operating voltage across said relay Winding duringthe lowest value of ballast resistance ,the combination with theaforementioned instrumentalities of a device connected across said railsand having the characteristic of conducting current when and only whenthe voltage across said relay winding rises above the normal operatingvalue.

4. In a railway signaling track circuit of the type comprising trackrails, a track relay having a winding connected across said rails, and asource of current also connected across said rails and adjusted tomaintain the normal operating voltage across said relay Winding duringthe lowest value of ballast resistance, the combination with theaforementioned instrumentalities of an electrolytic cell connectedacross said rails and having an electrolyte and electrodes characterizedby the fact that gas is evolved when Cltllht flows through the cell,said cell being adjusted to conduct current when and only when thevoltage across said relay winding rises a given amount above the normalopcrating value.

5; In a railway signaling track circuit of the type comprising trackrails, a track relay having a winding connected across said rails, and asource of current also connected across said rails and adjusted tomaintain the normal operating voltage across said relay winding duringthe lowest value of ballast resistance, the combination with theaforementioned instrumentalities of a transformer having its primaryconnected across said rails, and an electrolytic cell connected with thesecondary of said transformer, said cell being adjusted 'to conductcurrent when and only when the voltage across the cell rises above thenormal operating voltage across said relay winding multiplied by theratio of said transformer.

In testimony whereof l' fiix my signature.

' SAMUEL M. LUCAS.

